Patentable/Patents/US-8463599
US-8463599

Bandwidth extension method and apparatus for a modified discrete cosine transform audio coder

PublishedJune 11, 2013
Assigneenot available in USPTO data we have
Inventorsnot available in USPTO data we have
Technical Abstract

A method includes defining a transition band for a signal having a spectrum within a first frequency band, where the transition band is defined as a portion of the first frequency band, and is located near an adjacent frequency band that is adjacent to the first frequency band. The method analyzes the transition band to obtain a transition band spectral envelope and a transition band excitation spectrum; estimates an adjacent frequency band spectral envelope; generates an adjacent frequency band excitation spectrum by periodic repetition of at least a part of the transition band excitation spectrum with a repetition period determined by a pitch frequency of the signal; and combines the adjacent frequency band spectral envelope and the adjacent frequency band excitation spectrum to obtain an adjacent frequency band signal spectrum. A signal processing logic for performing the method is also disclosed.

Patent Claims
19 claims

Legal claims defining the scope of protection, as filed with the USPTO.

1

1. A method comprising: defining a transition band for a signal having a spectrum within a first frequency band, said transition band defined as a portion of said first frequency band, said transition band being located near an adjacent frequency band that is adjacent to said first frequency band; analyzing said transition band to obtain transition band spectral data; analyzing said transition band spectral data to obtain a transition band spectral envelope and a transition band excitation spectrum; and generating an adjacent frequency band signal spectrum using said transition band spectral data comprising: estimating an adjacent frequency band spectral envelope; generating an adjacent frequency band excitation spectrum, using said transition band spectral data; and combining said adjacent band spectral envelope and said adjacent frequency band excitation spectrum to generate said adjacent frequency band signal spectrum.

2

2. The method of claim 1 , wherein generating an adjacent frequency band excitation spectrum, using said transition band spectral data, further comprises: generating said adjacent frequency band excitation spectrum by periodic repetition of at least a part of said transition band excitation spectrum with a repetition period determined by a pitch frequency of said signal.

3

3. The method of claim 2 , wherein generating said adjacent frequency band excitation spectrum, further comprises: mixing said adjacent frequency band excitation spectrum generated by periodic repetition of at least a part of said transition band excitation spectrum with a pseudo-noise excitation spectrum within said adjacent frequency band.

4

4. The method of claim 3 , further comprising: determining a mixing ratio, for mixing said adjacent frequency band excitation spectrum and said pseudo-noise excitation spectrum, using a voicing level estimated from said signal.

5

5. The method of claim 4 , further comprising: filling any holes in said adjacent frequency band excitation spectrum due to corresponding holes in said transition band excitation spectrum using said pseudo-noise excitation spectrum.

6

6. The method of claim 1 , wherein estimating an adjacent frequency band spectral envelope, further comprises: estimating said signal's energy in said adjacent frequency band.

7

7. The method of claim 1 , further comprising: combining said spectrum within said first frequency band and said adjacent frequency band signal spectrum to obtain a bandwidth extended signal spectrum and a corresponding bandwidth extended signal.

8

8. A method comprising: defining a transition band for a signal having a spectrum within a first frequency band, said transition band defined as a portion of said first frequency band, said transition band being located near an adjacent frequency band that is adjacent to said first frequency band; analyzing said transition band to obtain a transition band spectral envelope and a transition band excitation spectrum; estimating an adjacent frequency band spectral envelope; generating an adjacent frequency band excitation spectrum by periodic repetition of at least a part of said transition band excitation spectrum with a repetition period determined by a pitch frequency of said signal; and combining said adjacent frequency band spectral envelope and said adjacent frequency band excitation spectrum to obtain an adjacent frequency band signal spectrum.

9

9. The method of claim 8 , wherein estimating an adjacent frequency band spectral envelope, further comprises: estimating said signal's energy in said adjacent frequency band.

10

10. The method of claim 9 , further comprising: combining said spectrum within said first frequency band and said adjacent frequency band signal spectrum to obtain a bandwidth extended signal spectrum and a corresponding bandwidth extended signal.

11

11. The method of claim 10 , wherein generating said adjacent frequency band excitation spectrum, further comprises: mixing said adjacent frequency band excitation spectrum generated by periodic repetition of at least a part of said transition band excitation spectrum with a pseudo-noise excitation spectrum within said adjacent frequency band.

12

12. The method of claim 9 , further comprising: determining a mixing ratio, for mixing said adjacent frequency band excitation spectrum and said pseudo-noise excitation spectrum, using a voicing level estimated from said signal.

13

13. The method of claim 9 , further comprising: filling any holes in said adjacent frequency band excitation spectrum due to corresponding holes in said transition band excitation spectrum using said pseudo-noise excitation spectrum.

14

14. A device comprising: an input where a signal is provided; a processor coupled to the input wherein the processor is configured to: define a transition band for the signal having a spectrum within a first frequency band, said transition band defined as a portion of said first frequency band, said transition band being located near an adjacent frequency band that is adjacent to said first frequency band; analyze said transition band to obtain a transition band spectral envelope and a transition band excitation spectrum; estimate an adjacent frequency band spectral envelope; generate an adjacent frequency band excitation spectrum by periodic repetition of at least a part of said transition band excitation spectrum with a repetition period determined by a pitch frequency of said signal; and combine said adjacent frequency band spectral envelope and said adjacent frequency band excitation spectrum to obtain an adjacent frequency band signal spectrum.

15

15. The device of claim 14 , wherein said processor is further configured to: estimate said signal's energy in said adjacent frequency band.

16

16. The device of claim 15 , wherein said processor is further configured to: combine said spectrum within said first frequency band and said adjacent frequency band signal spectrum to obtain a bandwidth extended signal spectrum and a corresponding bandwidth extended signal.

17

17. The device of claim 15 , wherein said processor is further configured to: mix said adjacent frequency band excitation spectrum generated by periodic repetition of at least a part of said transition band excitation spectrum with a pseudo-noise excitation spectrum within said adjacent frequency band.

18

18. The device of claim 17 , wherein processor is further configured to: determine a mixing ratio, for mixing said adjacent frequency band excitation spectrum and said pseudo-noise excitation spectrum, using a voicing level estimated from said signal.

19

19. The device of claim 18 , wherein said processor is further configured to: fill any holes in said adjacent frequency band excitation spectrum due to corresponding holes in said transition band excitation spectrum using said pseudo-noise excitation spectrum.

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Patent Metadata

Filing Date

February 4, 2009

Publication Date

June 11, 2013

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Cite as: Patentable. “Bandwidth extension method and apparatus for a modified discrete cosine transform audio coder” (US-8463599). https://patentable.app/patents/US-8463599

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